1. Oversize control is required for such operations as contour milling, veneer gluing etc. You can access it through Woodwork Design menu item Workpiece Oversize.
2. By default, the system automatically applies oversize to a fill material. You need to click on the part you want to set oversize to. Now enter an oversize value. Click "Apply" to add oversize to all the edges of your model or click on some particular edge to apply oversize to a given edge only. Green contour shows you the size of a blank, and yellow one shows additional oversize.